Crystallographic interface control of the plasmonic photocatalyst consisting of gold nanoparticles and titanium(iv) oxide.

A big question in the field of plasmonic photocatalysis is why a typical photocatalyst consisting of gold nanoparticles and rutile titanium(iv) oxide (Au/R-TiO 2 ) usually exhibits activity much higher than that of Au/anatase TiO 2 (Au/A-TiO 2 ) under visible-light irradiation. Shedding light on the origin should present important guidelines for the material design of plasmonic photocatalysts. Au nanoparticles (NPs) were loaded on ordinary irregular-shaped TiO 2 particles by the conventional deposition precipitation method. Transmission electron microscopy analyses for the Au/TiO 2 particles ascertain that faceting of Au NPs is induced on R-TiO 2 by using a domain-matching epitaxial junction with the orientation of (111) Au //(110) R-TiO 2 , whereas non-faceted hemispherical Au NPs are exclusively formed on A-TiO 2 . The faceting probability of Au NPs ( P f ) on R-TiO 2 increases with decreasing Au particle size ( d Au ) to reach 14% at d Au = 3.6 nm. A clear positive correlation between the photocatalytic activity and P f in several test reactions indicates that the heteroepitaxial junction-induced faceting of Au NPs is the principal factor for governing the plasmonic photocatalytic activity of Au/TiO 2 . In light of this finding, R-TiO 2 nanorods with a high percentage (95%) of {110} facets were hydrothermally synthesized and used for the support of Au NPs. Consequently, the P f value increases to as much as 94% to enhance the photocatalytic activity with respect to that of Au/R-TiO 2 with P f = 14% by factors of 2.2-4.4 depending on the type of reaction.